1) Formative time lag depends on the mechanism of the avalanche growth in gap. The formative time lag is usually
a. Much shorter than the statistical time lag
b. Much greater than the statistical time lag
c. Equal to the statistical time lag
d. None of these
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2) The statistical time lag depends upon the
a. Size of gap
b. Quantity of radiation that produces the primary electrons
c. Amount of pre-ionization preset gap
d. All of these
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3) According to the Paschen’s Law, the breakdown voltage of a uniform field gap is
a. Directly proportional to the gas pressure and inversely proportional to the electrode gap
b. Inversely proportional to the gas pressure and directly proportional to the electrode gap
c. Directly proportional to the both electrode gap and gas pressure
d. Inversely proportional to the both electrode gap and gas pressure
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Answer
Explanation
Related Ques
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ANSWER: Directly proportional to the both electrode gap and gas pressure
Explanation:
No explanation is available for this question!
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4) For the high voltage conductors at high pressures, if the voltage is positive then the corona appears as a
a. Uniform bluish white sheath
b. Reddish glowing spots
c. Uniform greenish spots
d. None of these
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5) Field in case of rod gaps and sphere gaps are
a. Uniform, uniform
b. Uniform, non-uniform
c. Non-uniform, uniform
d. Non-uniform, non-uniform
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6) In Breakdown tests, the tests voltages required for these tests are usually of the order of
a. 0 – 10 kV
b. 20 – 50 kV
c. 50 – 100 kV
d. 100 – 200 kV
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7) The increase in liquid hydrostatic pressure
a. Increases the breakdown strength
b. Decreases the breakdown strength
c. Does not affect the breakdown strength
d. None of these
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8) In case of solid particles present in the liquid and in case of presence of only gas bubbles in liquids, the direction of force is towards
a. Areas of maximum stress, areas of minimum stress
b. Areas of maximum stress, areas of maximum stress
c. Areas of minimum stress, areas of maximum stress
d. Areas of minimum stress, areas of minimum stress
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Answer
Explanation
Related Ques
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ANSWER: Areas of maximum stress, areas of minimum stress
Explanation:
No explanation is available for this question!
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9) According to the Bubble theory, once a bubble is formed, it will elongate in the direction of electric field under the influence of electrostatic forces. During elongation the volume of bubbles
a. Increases
b. Decreases
c. Remains constant
d. None of these
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10) According to the Stressed Oil Volume theory, the breakdown strength is
a. Directly proportional to the stressed oil volume
b. Directly proportional to the square of the stressed oil volume
c. Inversely proportional to the stressed oil volume
d. None of these
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Answer
Explanation
Related Ques
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ANSWER: Inversely proportional to the stressed oil volume
Explanation:
No explanation is available for this question!
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11) Treeing phenomenon is observed in
a. Capacitors
b. Cables
c. Insulators
d. Only (a) and (b)
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12) The liquid dielectrics contain voids or cavities within the medium or at the boundaries between the dielectric and the electrodes. The electric field strength in the voids is
a. Lower than that across the dielectric
b. Higher than that across the dielectric
c. Equal to that across the dielectric
d. None of these
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13) For very small cavities, discharge inception voltage
a. Decreases as the cavity depth increases
b. Increases as the cavity depth increases
c. Remains unaffected as the cavity depth increases
d. None of these
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14) Which among the following is not an example of impregnants?
a. Mineral oil
b. Chlorinated diphenyl
c. Vegetable oils
d. None of these
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15) The example of artificial fibre is
a. Rayon
b. Cotton
c. Flax
d. Silk
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16) The most commonly used insulating materials for low and medium voltage cables is
a. Polyethylene
b. Porcelain
c. PVC
d. Vulcanized rubber
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17) In paper based laminated construction, the typical value of dielectric constant and dielectric loss factor is
a. 3.5, 0.0015
b. 2.5, 0.0020
c. 3.5, 0.0025
d. 2.5, 0.0035
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18) The resin bonded paper bushings are designed to operate at a maximum radial stress of
a. 5 kV/cm
b. 10 kV/cm
c. 15 kV/cm
d. 20 kV/cm
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19) Resins and varnishes are commonly used in
a. Generators and motors
b. Cables
c. Transformers
d. Circuit breakers
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20) The commonly used materials for HV insulation is
a. Paper-oil insulation
b. Polyester resin
c. Ceramic
d. PVC
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21) The disadvantages of resonant transformers is
a. Pure sine wave output
b. No high power arcing
c. No repeated flashovers
d. Additional variable chokes
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22) In a series RLC circuit, the wave front and wave tail times are controlled by changing the value
a. R only
b. R and L simultaneously
c. R and C simultaneously
d. L and C simultaneously
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23) In a multistage impulse generator, for producing very high voltages, a bank of capacitors is
a. Charged in parallel and then discharged in series
b. Charged in series and then discharged in parallel
c. Charged in parallel and then discharged in parallel only
d. Charged in series and then discharged in series only
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Answer
Explanation
Related Ques
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ANSWER: Charged in parallel and then discharged in series
Explanation:
No explanation is available for this question!
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24) For producing large values of impulse currents, a number of capacitors are charged in
a. Parallel and discharged in series
b. Parallel and discharged in parallel
c. Series and discharged in series
d. Series and discharged in parallel
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25) In large impulse generators, the spark gaps are generally
a. Sphere gaps
b. Hemispherical gaps
c. Square gaps
d. Either (a) or (b)
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26) A Capacitance Voltage Transformer can be connected to a
a. High impedance device
b. Low impedance device
c. Relay coil
d. Only (b) and (c)
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27) The attractive force between the electrodes of a parallel plate capacitor is
a. Directly proportional to the square of the applied voltage between plates
b. Directly proportional to the capacitance between the plates
c. Inversely proportional to the square of the separation between the plates
d. All of these
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28) The series capacitor peak voltmeter is suitable for
a. Positive half cycle
b. Negative half cycle
c. Sinusoidal waveform
d. All of these
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29) For voltage measurements, the gap which gives highest accuracy is
a. Sphere gaps
b. Field gaps
c. Rod gaps
d. None of these
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30) The sparkover voltage
a. Increases with humidity
b. decreases with the partial pressure of water vapour in air
c. Humidity effect decreases with the size of spheres
d. Humidity is minimum for uniform field gaps
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31) The expected life at the rated stress can be determined by conducting long duration life tests at increased stress for
a. Less than 1 hr
b. 1 hr to about 1000 hr
c. More than 1000 hr
d. None of these
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32) Impulse testing of transformers is done using
a. Full wave standard impulse
b. Chopped wave standard impulse
c. Half wave standard impulse
d. Only (a) and (b)
e. None of these
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33) Failure during switching impulse tests are can be determined by
a. Visible in oscillograms
b. Loud noise produced
c. External flashovers
d. All of these
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34) For operating power frequency voltages, a surge arrester has to be a
a. Conductor
b. Non-conductor
c. Semiconductor
d. None of these
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35) For the measurement of radio interference voltages, the detector circuit is provided with a measuring device to measure
a. Average value
b. Peak value
c. Quasi-peak value
d. All of these.
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